Builders for Climate Action thinks so. A new study from Natural Resources Canada and the coalition Builders for Climate Action suggests that measuring a home’s energy efficiency alone does not provide a comprehensive enough picture of its overall emissions.
The new report argues that getting a more comprehensive idea of a building’s carbon output is key to helping Canada achieve its target of going carbon neutral by 2050.
Currently, the National Building Code focuses on reducing a home’s carbon footprint by reducing its energy consumption.
Builders for Climate Action, however, say that measuring energy efficiency alone doesn’t account for the emissions produced in the manufacture of building materials, what the study authors call material carbon emissions (MCE). Nor does the Code account for the emissions generated by the energy sources that power a building.
“The current regulatory framework addresses only energy efficiency and ignores MCE and fuel source emissions,” say the study authors.
They argue that this is a critical oversight because “even if all operational carbon emissions (OCE) from Canadian buildings reach net-zero, the substantial volume of emissions from the production of materials used to build Canadian homes will continue to be a leading source of housing sector emissions.”
Research Shows that Swapping Materials Can Make a Bigger Impact Than Improving Energy Efficiency
The report proposes that the building industry adopt a metric the authors call Carbon Use Intensity (CUI) to determine a home’s carbon footprint. This metric looks at a building’s energy efficiency plus the carbon intensity of the energy sources it draws from (its OCE), as well as its MCE.
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The research team studied the impact of OCE and MCE on 3 types of Canadian homes in 5 Canadian cities.
Using energy modelling data for the homes, as well as NRCan’s Material Carbon Estimator tool to determine the global warming potential (GWP) of each building material, researchers found that “material selection can impact the total emissions of a new home by as much as 842 kg CO2e/m2 without changing the design or performance of the home.”
They point to insulation as an example; “a cautionary warning that the pursuit of energy efficiency without consideration of material emissions can cause dramatic increases in overall emissions.”
If a builder increases insulation with a high-carbon material like spray polyurethane foam, the reductions in OCE achieved by the extra insulation won’t offset the hike in MCE, and, therefore, the hike in the home’s total emissions.
Measuring CUI provides a framework for balancing building decisions and making choices that will reduce total emissions associated with the home.
Going Forward
Whether this holistic approach will have an impact on regulatory frameworks remains to be seen.
The study authors, however, hope that adopting CUI as a metric will allow a more flexible and effective approach to reducing total emissions by the housing sector, bringing immediate gains at a crucial time when every kg of CO2 matters.
Image credit: Avel Chuklanov
